Exemplary embodiments of the present invention relate to a sliding sleeve blank suitable for creating sliding sleeves for steering spindle shafts of motor vehicle steering spindle assemblies and the motor vehicle steering spindle assemblies themselves.
Known steering spindle assemblies have a steering spindle shaft, which has a shaft section with an external toothing system at its end, and a sliding sleeve, which has an internal toothing system over a large part of its length. The internal toothing system of the sliding sleeve is geared moveably with the external toothing system of the steering spindle shaft in the steering spindle assembly. To achieve as direct a steering torque transfer of the steering spindle as possible, while at the same time creating a connection between the sliding sleeve and the steering spindle shaft, which functions quietly during operation, the steering spindle shaft is typically coated with plastic.
It is known to produce the toothing system of the sliding sleeve by hammering, which achieves a highly precise configuration of the gearing. During the hammering, a pin with a toothed contour is inserted into the hollow sliding sleeve; then the sleeve is acted on radially from the outside by hammering, wherein the inner contour of the sleeve receives the toothing contour of the pin, while the cross-section of the sleeve is reduced at the same time. The external contour of the sleeve remains smooth.
For constructional reasons, such sliding sleeves are equipped with a collar at its end facing away from the direction of the torsional damper in an assembled state, on the connection of which winged webs are provided, by means of which the sleeve is immersed into corresponding recesses of the torsional damper located on one end of the steering spindle assembly. In this way, the sleeve adopts a defined angular position.
The collar, which forms a contact at the torsional damper, is located in the section until the preparation for being acted on by means of hammering. No hammering from the outside can operate in the region in which the wings and the collar are present.
Thus, the sliding sleeve arising due to the above-described toothing system is restricted with respect to the sliding path. This is therefore disadvantageous, since, when the engine is being fitted into the vehicle, the steering spindle is to be withdrawn as far as possible so that it does not collide with the engine. In this instance, the rotational angle position must remain in a maintained state at the same time, so that assembly of the steering spindle on the steering gear is unhindered.
If, however, the steering spindle is withdrawn accordingly, this requirement cannot be fulfilled since, due to the lack of internal toothing system at the one end of the sliding sleeve, the steering spindle can be freely rotated.
Essentially, hollow cylindrical precision parts made from metal can be reshaped in cold impact extrusion instead of by hammering. Such a method is disclosed in German Patent Publication DE 10 2005 033 188 A1. Here, bar stock is used as the raw material and, after this has been trimmed, a raw component is produced, which has its external lateral area trimmed and has an inner bore-hole added to it. The raw part is reshaped with a desired inner and outer geometry by cold impact extrusion and an external toothing system is provided.
A length-adjustable steering spindle, which enables withdrawal of the same during the assembly of the engine, is also disclosed in German Patent Publication DE 19 750 005 C1. Here, the length-adjustable steering spindle has at least two raw pieces that are arranged coaxially and that are axially displaceable, wherein one of them is mounted to transfer a torsional moment by positive engagement. The outer and inner peripheral contours of the inner and outer profile are formed by curved sections with alternating radii of curvature; a circumferential gap space is present between both profiles. A gliding sleeve made from macro-molecular material is received in the gap space, which rests against the walls of the profile that delineate the gap space along its peripheral contour only in sections and according to choice. The gliding sleeve rests alternatingly on convex sections of the inner profile and on concave sections of the outer profile.
Exemplary embodiments of the present invention provide a steering spindle assembly that can be constructed in a simple and cost-effective manner, which still enables the retention of a rotational angle position of the spindle on the steering gear during axial displacement of the steering spindle at the sliding sleeve.
In order to create a motor vehicle steering spindle assembly according to the invention, first a sliding sleeve blank is provided according to the invention, which enables a sliding sleeve for a steering spindle shaft of a motor vehicle steering spindle assembly to be provided. The blank has a cylindrical shape and has a section on its one end, which comprises a circumferential collar and winged webs extending radially away from the collar to the end of the sleeve.
The sliding sleeve blank according to the invention is now a cold impact extrusion component, which has been directly obtained during the creation of an internal toothing system, which extends over part of the length of the above-mentioned section. This section is indeed any section that cannot be acted on by hammering.
In this way, a component is now provided by the sliding sleeve blank according to the invention, which, during further action by means of hammering, can be reshaped into a sliding sleeve in a known manner, which has a further, hammered toothing system.
The sliding sleeve made from the sliding sleeve blank according to the invention therefore now has two internal toothing systems: a first, which extends from the section having one of the sliding sleeves to the section having the collar, wherein this internal toothing system is producing by hammering, and a second, so-called preliminary toothing system, which is present in the section that rests on the second end. A sliding sleeve thus has been created having an internal toothing system over virtually its entire length and that, in this respect, enables a longer, controlled sliding path for a steering spindle shaft to be prepared.
A motor vehicle steering spindle assembly according to the invention comprises such a steering spindle shaft with an external toothing system, which is part of the steering spindle, in which the steering spindle shaft can be received in an axially displaceable manner. The sliding sleeve is advantageously made from a sliding sleeve blank according to the invention and thus has the known hammered internal toothing system, which extends from the one first end of the sliding sleeve in the direction of a section that is near to the second end of the sleeve, which section has the collar and the winged webs that extend radially away. In one installation position of the steering spindle assembly, the hammered internal toothing system is in sliding engagement with the external toothing system of the steering spindle shaft.
Furthermore, the steering spindle shaft according to the invention has a preliminary toothing system according to the invention over one part of the length of the cited section, which is geared with the external toothing system in one assembly position of the steering spindle shaft. Here, a rotational angle position, which has engaged the steering spindle shaft with the toothing system in the installation position, or which was positioned with the steering spindle shaft, is retained by transferring the steering spindle shaft from the hammered internal toothing system to the preliminary toothing system.
The length of the external toothing system of the steering spindle shaft can be selected in such an advantageous way that the steering spindle shaft is guided without interruption through the hammered internal toothing system and through the preliminary toothing system of the sliding sleeve during the transfer from the installation position to the assembly position.
The external toothing system of the steering spindle shaft can be provided by a plastic coating.
Furthermore, the preliminary toothing system of the steering spindle shaft can have such a tooth size that a tolerance compensation gap is provided between the preliminary toothing system and the external toothing system in the assembly arrangement. Production tolerances, such as those that arise due to cold impact extrusion, are hereby compensated for.
A further possibility for the compensation of production tolerances can be created by the fact that the toothing system has a missing tooth in the sliding sleeve in the hammered region. In the hammered region, the steering spindle shaft can then have a block tooth. In the preliminary toothing region of the sliding sleeve, there is, however, only one missing tooth.
These and other advantages are demonstrated by the description below with reference to the accompanying figures.